Various approaches are known in the art for passing cable through a wellhead into the interior of the well head casing. Cugini, et al, U.S. Pat. No. 3,437,149 and Sipowicz U.S. Pat. No. 4,041,240, disclose pressure-sensitive cable feed-thru means which extend from the exterior of a wellhead construction through a pressure zone in the wellhead into the interior of a wellhead casing. Therein, coupling means are provided at both ends of the cable feed-thru means. Conductors are embedded in a dielectric material which is moulded within, and protected by, a rigid metal casing or shell.
One problem facing the art today resides in the fact that the potting compounds holding the conductors in place are invariably attacked by the hot oil and hot fluids used to facilitate the pumping of individual oil wells. These fluids attack externally by penetrating the coupling which attaches the lower connector to the feed-thru mandrel, and internally by capillary action of the conductors within the downhole electrical cable. Both actions may result in an electrical failure by means of an electrical shorting action.
In addition, the high pressure differentials cause minute cracks in the rigid bonding materials used, thereby leading to leaks in the system which if not detected may have the effect of causing blow outs in the well whenever a conductor, or pair of conductors is broken loose from the bonding material.
Thus, a basic problem with some prior art techniques resides in the maintenance of the integrity of the dielectric material which encases the conductors, and which passes from a low pressure environment to a high pressure environment. Yet another problem facing the art today is the difficulty and often troublesome process of installing the wellhead conductor in the various types of casing heads in use throughout the petroleum producing industry.
The principal prior art cited in the parent application are U.S. Pat. No. 3,945,700, No. 4,154,302 and No. 4,426,124. Also, an accumulated listing of related patents appears in the parent application.
In view of the foregoing, it is an object of the present invention to provide a new and improved downhole and surface electrical feed-thru connector assembly which will maintain the dielectric strength of the materials which encase the electrical conductors and simultaneously prevent any pressure leaks from developing within and around the electrical conductor.
It is another object of the present invention to provide an improved downhole and surface electrical feed-thru connector assembly wherein the dielectric material is capable of expansion and contraction while ensuring a rigid seal around the electrical conductors and within the mandrel and connector shells within which they are housed or encased.
It is still another object of the present invention to provide an improved downhole and surface electrical feed-thru connector assembly which characterizes a mandrel connector capable of variations in length and which is readily adaptable to accommodate specific wellhead requirements.
It is still another object of the present invention to provide the capability of adapting the improved electric feed-thru connector assembly on a variety of wellhead configurations.
These and other objects of the present invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings which form part of the specification, with the understanding, however, that the invention is not confined to a strict conformity with the drawings but may be changed or modified so long as such changes or modifications make no material departure from the salient features of the invention as expressed in the appended claims.